JP2001346121A - Display device with two-screen function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device with a two-screen function that can automatically select one-screen or two-screens without the need for an external switching signal. SOLUTION: A synchronizing signal presence detection section 1-1 detects the presence of a synchronizing signal of a video signal from a 1st input system. A synchronizing signal presence detection section 1-2 detects the presence of a synchronizing signal of a video signal from a 2nd input system. The synchronizing signal detection sections 1-1, 1-2 give the detection results to a 2-screens/1-screen changeover section 1-3. The two-screens/one-screen changeover section 1-3 allows a display device 1-4 to display video images in two-screens from the 1st and 2nd input systems when the synchronizing signal detection sections 1-1, 1-2 indicate the presence of the synchronizing signal on the basis of the detection results from the synchronizing signal detection sections 1-1, 1-2. When either of the detection results indicates the presence of the synchronizing signal, the two-screens/1-screen changeover section 1-3 allows the display device 1-4 to display the video image from the input system with the synchronizing signal in one-screen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having a two-screen function for automatically switching between one screen and two screens.

[0002]

2. Description of the Related Art Conventionally, as a system using a display device with a two-screen function, there is a system disclosed in Japanese Patent Application Laid-Open No. 58-21981 (Document 1). In this system, a television receiver capable of displaying two screens is used. Normally, a general broadcast image is displayed on a large screen of the two screens of the television receiver, and information from a computer is displayed on a small screen for a counter program. (For example, reception number). When the operation button connected to the computer is pressed, a switching signal is sent from the computer to the television receiver, and the image on the large screen and the image on the small screen are switched.
New information from the computer (for example, the next reception number) is displayed on the large screen. After a lapse of a predetermined time, the image on the large screen and the image on the small screen of the television receiver are switched, and are restored to the original state.

[0003]

However, in the system disclosed in this document 1, a large screen and a small screen are always displayed. When there is no information to be displayed on the small screen, the system is left blank ( For example, blue back). In order to avoid this, it is possible to switch from one screen to two screens only when necessary. That is, when an operation button connected to the computer is pressed, a switching signal is sent from the computer to the television receiver, the screen is switched from one screen to two screens (two screens, a large screen and a small screen), and the computer is switched to the small screen. It is conceivable to display information from.

However, in this method, when switching from one screen to two screens, it is necessary to supply a switching signal to the television receiver. Therefore, when an image is transmitted from an input device such as a video deck, a control device that generates a switching signal is required. In addition, a connection terminal for a switching signal from the control device must be provided in the television receiver, and it is necessary to connect this connection terminal to a circuit that decodes the received switching signal and controls screen switching. . In addition, it is necessary to connect the control device and the television receiver with a switching signal cable in addition to the video signal cable. This complicates the connection and limits the connection distance.

On the other hand, Japanese Patent Application Laid-Open No. 2000-41196 (Reference 2) discloses a television receiver that detects the presence or absence of a synchronization signal of a video signal from a plurality of input systems, and detects an input system having a synchronization signal. For example, Japanese Patent Application Laid-Open No. H11-157572 discloses a technique for displaying information indicating that an image can be received on an input system without a synchronization signal on a screen. In this case, the user can select a desired input system with a small number of operations by skipping the input system in which information indicating that the image cannot be received is displayed. A technique for determining whether an image can be received by detecting the presence or absence of a synchronization signal is disclosed in Japanese Patent Laid-Open No. 1-23282.
Japanese Unexamined Patent Application Publication No. Hei 5-244450 (Literature 4), Japanese Unexamined Patent Publication No. Hei 10-69254 (Literature 5), and Japanese Unexamined Patent Publication No. Hei 10-301522 (Literature 6).

Document 2 does not disclose switching between one screen and two screens. However, in this document 2, when switching between one screen and two screens is performed, the following is performed. Technology is conceivable. In a television receiver, the presence or absence of a synchronization signal of a video signal from a plurality of input systems is detected, and information indicating that an input system having a synchronization signal can be received is notified that information can be received by an input system having no synchronization signal. Display information on the screen. When two input systems are selected and specified among the input systems on which information indicating that the image can be received is displayed, images from the selected two input systems are displayed on two screens, and one input system is displayed. Is selected and designated, the video from one selected and designated input system is displayed on one screen. In this case, the user selects and specifies the input system on the screen each time, and switching between one screen and two screens is not automatically performed.

The present invention has been made to solve such a problem, and an object of the present invention is to automatically switch between one screen and two screens without giving a switching signal from outside. It is an object of the present invention to provide a display device with a two-screen function capable of performing the following.

[0008]

In order to achieve the above object, the present invention detects the presence or absence of a synchronizing signal of a video signal from a first input system, and detects a video signal from a second input system. The presence / absence of a signal synchronization signal is detected.
And when the detection result of the presence / absence of the synchronization signal of the video signal from the second input system is the presence of the synchronization signal, the images from the first input system and the second input system are displayed on one display device on two screens. If one of the detection results of the presence / absence of the synchronization signal of the video signal from the first and second input systems has a synchronization signal, the video from the input system having the synchronization signal is displayed on one display device. This is displayed on the screen. According to the present invention, for example, when a synchronization signal of a video signal from the second input system is detected while a video from the first input system is displayed on the display device on one screen, In this case, two screens are displayed, and two images, that is, the image from the first input system and the image from the second input system, are simultaneously displayed. When the synchronizing signal of the video signal from the second input system is lost, one screen is automatically displayed and the first screen is displayed.
Only the video from the input system is displayed.

The present invention further comprises an input system selecting means for selecting two input systems specified from n (n ≧ 3) input systems as a first input system and a second input system. The system detects the presence or absence of a synchronization signal of a video signal from the first input system, detects the presence or absence of a synchronization signal of a video signal from the second input system, and detects images from the first and second input systems. When both the detection results of the presence / absence of the synchronizing signal of the signal indicate that the synchronizing signal is present, the images from the first input system and the second input system are displayed on one display device on two screens, and the first and second images are displayed. When one of the detection results of the presence or absence of the synchronization signal of the video signal from the input system has a synchronization signal, the video from the input system with the synchronization signal is displayed on one display device on one screen. is there. According to the present invention, two input systems specified from n (n ≧ 3) input systems are selected as the first and second input systems. For example, an image from the first input system is displayed on the display device. When the synchronization signal of the video signal from the second input system is detected while being displayed on one screen,
The screen is displayed, and two images, the image from the first input system and the image from the second input system, are displayed simultaneously. When the synchronization signal of the video signal from the second input system is lost,
One screen is automatically displayed, and only the video from the first input system is displayed.

Further, according to the present invention, based on a pulse of a synchronizing signal of a video signal from a first input system and a second input system, if the pulse cannot be confirmed until a predetermined time elapses, Alternatively, when the frequency of the pulse deviates greatly from the corresponding frequency of the display device, it is determined that there is no synchronization signal. According to the present invention, when the pulse of the synchronization signal is not confirmed until the predetermined time elapses, it is determined that there is no synchronization signal. Further, even if a pulse of the synchronization signal is confirmed before the predetermined time elapses, it is determined that there is no synchronization signal if the frequency of the pulse deviates greatly from the corresponding frequency of the display device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. [First Embodiment (Basic Example 1)] FIG. 1 is a block diagram showing a main part of a basic example 1 of a display device with a two-screen function according to the present invention. Referring to FIG. 1, reference numeral 1 denotes a display device with a two-screen function according to the present invention, which includes synchronization signal presence / absence detection units 1-1 and 1--1.
2, 2 screen / 1 screen switching section 1-3 and display device 1
-4. 2-1 and 2-2 are signal sources (input devices such as a video deck). The video input (video signal + sync signal) from the signal source 2-1 is a first input system, and the video input (video signal + sync signal) from the signal source 2-2 is a second input system.

In the display device 1 with a two-screen function,
A synchronization signal presence / absence detection section 1-1 detects the presence / absence of a synchronization signal of a video signal from the first input system, and
-2 detects the presence or absence of a synchronization signal of a video signal from the second input system. The detection results of the synchronization signal presence / absence detection units 1-1 and 1-2 are sent to a two-screen / one-screen switching unit 1-3.

The two-screen / one-screen switching section 1-3 receives a first input signal based on the detection results from the synchronization signal presence / absence detection sections 1-1 and 1-2, when both of the detection results indicate the presence of a synchronization signal. The images from the system and the second input system are displayed on the display device 1-4 in two screens (see FIG. 2A).

The two-screen / one-screen switching unit 1-3, based on the detection results from the synchronization signal presence / absence detection units 1-1 and 1-2, determines whether any one of the detection results has a synchronization signal.
Display image from input system with sync signal on display device 1-
4 is displayed on one screen (see FIG. 2B).

[Second Embodiment (Basic Example 2)] FIG. 3 is a block diagram showing a main part of a basic example 2 of a display device with a two-screen function according to the present invention. In the figure, reference numeral 1 'denotes a display device with a two-screen function according to the present invention, which includes synchronization signal presence / absence detection units 1-1 and 1-2, a two-screen / one-screen switching unit 1-3, a display device 1-4, An input system selector 1-5 and a setting data storage 1-6 are provided. 2-1 to 2-n are signal sources (input devices such as a video deck). The input data selection condition is set in the setting data storage unit 1-6.
The selection condition for the setting data storage unit 1-6 is the signal source 2-1.
N (n ≧ 3) video inputs (video signal +
(Synchronization signal), that is, the user sets arbitrary two of the n input systems.

In the display device 1 'with a two-screen function, the input system selection section 1-5 includes a setting data storage section 1-6.
Signal sources 2-1 to 2 based on the selection conditions set in
Two input systems specified by the user are selected from the n input systems of -n as the first and second input systems. For example, the input system of the signal source 2-1 is selected as a first input system, and the input system of the signal source 2-2 is selected as a second input system.

The synchronizing signal presence / absence detecting section 1-1 detects the presence / absence of a synchronizing signal of the video signal from the first input system selected by the input system selecting section 1-5.
Detects the presence or absence of a synchronization signal of a video signal from the second input system selected by the input system selection unit 1-5. The detection result of the synchronization signal presence / absence detection units 1-1 and 1-2 is 2 screens / 1
It is sent to the screen switching unit 1-3.

The two-screen / one-screen switching section 1-3 is based on the detection results from the synchronization signal presence / absence detection sections 1-1 and 1-2. The images from the system and the second input system are displayed on the display device 1-4 in two screens (see FIG. 2A).

The two-screen / one-screen switching unit 1-3, based on the detection results from the synchronization signal presence / absence detection units 1-1 and 1-2, determines whether any one of the detection results has a synchronization signal.
Display image from input system with sync signal on display device 1-
4 is displayed on one screen (see FIG. 2B).

As can be seen from the basic examples 1 and 2 described above, in the present embodiment, the presence or absence of the synchronizing signal of the video signal from the first and second input systems is detected, and based on the detection result, Switching between the screen and the two screens is performed automatically. This allows automatic switching between one screen and two screens without providing a switching signal from the outside, and eliminates the need for a control device that generates a switching signal. Further, a connection terminal for a switching signal from the control device need not be provided on the display device side, and there is no need to connect this connection terminal to a circuit that decodes the received switching signal and controls the screen switching. Further, there is no need to connect the control device and the display device with a switching signal cable in addition to the video signal cable, so that the connection does not become complicated and there is no problem that the connection distance is restricted. Further, in the basic example 2, the user specifies the input system, but if the selection condition is set in the setting data storage unit 1-6, the switching between the single screen and the two screens is automatically performed according to the setting. Done. Therefore, it is not necessary to select and designate one screen or two screens each time, unlike the technique considered from the literature 2.

[Embodiment 3 (Specific Example 1)] FIG. 4 is a block diagram of a display device with a two-screen function that embodies the basic example 2. In the figure, a, c, e, g, and i are video signal terminals, b, d, f, h, and j are synchronization signal terminals.
The video signal terminal a and the synchronization signal terminal b are supplied with the video signal and the synchronization signal from the input system I, and the video signal terminal c and the synchronization signal terminal d are provided with the video signal and the synchronization signal from the input system II. And a video signal terminal e
A video signal and a synchronization signal from the input system III are given to the synchronization signal terminal f, and a video signal and a synchronization signal from the input system IV are given to the video signal terminal g and the synchronization signal terminal h. A video signal and a synchronization signal from the input system V are supplied to the signal terminal i and the synchronization signal terminal j.

101 is a selector, 102 and 103 are analog-to-digital converters (A / D converters), 104 and 105
Is an image processing unit, 106 and 107 are synchronization processing units, 108 is a screen synthesis / switching unit, 109 and 110 are synchronization signal generation units,
111 is a control microcomputer, 112 is a display device, 113
Is an operation button, and 114 is an on-screen device (OS
D) and 115 are nonvolatile memories.

The selector 101 selects, based on a selection condition from the control microcomputer 111, two input systems specified by the selection condition as first and second input systems. The A / D converter 102 receives the video signal of the first input system selected by the selector 101 as an input, converts the video signal into a digital video signal, and sends the digital video signal to the image processor 104. The A / D conversion unit 103 receives the video signal of the second input system selected by the selector 101 as an input, converts the video signal into a digital video signal, and sends the digital video signal to the image processing unit 105. Image processing units 104 and 10
Reference numeral 5 performs resolution conversion and enlargement / reduction processing on the digital video signals from the A / D converters 102 and 103. The screen combining / switching unit 108 includes image processing units 104 and 105
A digital video signal that has been subjected to resolution conversion and enlargement / reduction processing is input, and two-screen synthesis and one-screen / two-screen switching processing are performed. The output of the screen combining / switching unit 108 is finally given to the display device 112.

The synchronization processing unit 106 receives the synchronization signal of the first input system selected by the selector 101 as an input, detects the polarity of the synchronization signal, and adjusts the polarity and level. The synchronization processing unit 107 receives the synchronization signal of the second input system selected by the selector 101 as an input, detects the polarity of the synchronization signal, and adjusts the polarity and level. Synchronization processing unit 106
The synchronization signal whose polarity and level are adjusted in is supplied to the synchronization signal generation unit 109. The synchronization signal whose polarity and level are adjusted by the synchronization processing unit 107 is supplied to the synchronization signal generation unit 110. Further, the synchronization signals and the polarity detection information from the synchronization processing units 106 and 107 whose polarity and level are adjusted are provided to the control microcomputer 111.

The synchronizing signal generator 109 includes an A / D converter 1
02, a synchronizing signal for the image processing unit 104, a screen synthesizing / switching unit 108, and the display device 11.
2 is generated. The synchronization signal generation unit 110
It generates a sampling clock for the A / D conversion unit 103, a synchronization signal for the image processing unit 105, and a synchronization signal for the screen combining / switching unit 108 and the display device 112.

The control microcomputer 111 includes an image processing unit 104
And output the setting data to the A / D converter 10.
Optimum image processing is performed on the digital video signals from 2 and 103. The control microcomputer 1
Reference numeral 11 outputs setting data to the synchronization signal generation units 109 and 110 so that the sampling clock to the A / D conversion units 102 and 103 and the synchronization signal to the image processing units 104 and 105 have optimal timing. . Further, the control microcomputer 111 outputs the setting data to the display device 112 to make the operation of the display device 112 optimal.
The setting data is output to the screen combining / switching unit 108,
Combining two screens and switching between one screen and two screens are performed. The control microcomputer 111 operates according to a program stored in the internal memory.

In the nonvolatile memory 115, whether the switching between one screen and two screens is automatic switching or manual switching,
Settings regarding which input system to select as a video to be displayed on the screen are stored. This nonvolatile memory 1
The setting to 15 is performed by the user via the operation button 113. The OSD 114 is provided between the control microcomputer 111 and the screen combining / switching unit 108 so that the user can recognize the setting operation.

[Settings by User] The user can control the control microcomputer via the operation buttons 113 to determine whether switching between one screen and two screens is automatic switching or manual switching, or which input system is to be selected as two screens. Input to 111. The control microcomputer 111 sends the setting data input by the user to the OSD 14, and displays the setting contents in a menu. The control microcomputer 111 stores the setting data in the nonvolatile memory 115.

[Automatic switching between one screen and two screens] Based on the setting data stored in the non-volatile memory 115, the control microcomputer 111 determines whether the setting from the user is automatic switching between one screen and two screens and manually switched. Is determined.
In the case of automatic switching between one screen and two screens, setting data on which input system is selected as two input systems is read, and the setting data is given to the selector 101 as a selection condition. The selector 101 controls the control microcomputer 1
Based on the selection condition given from 11, the two input systems specified by the selection condition are selected from the input systems I to V as the first and second input systems. For example,
The input system I is selected as a first input system, and the input system II is selected as a second input system.

The video signal of the first input system is supplied to the A / D converter 102. The video signal of the second input system is A /
This is provided to D conversion section 103. The synchronization signal of the first input system is provided to the synchronization processing unit 106. The synchronization signal of the second input system is provided to the synchronization processing unit 107.

The synchronization processing unit 106 detects the polarity of the synchronization signal of the first input system, adjusts the polarity and level, and supplies the synchronization signal and the polarity detection information to the control microcomputer 111. The synchronization processing unit 107 detects the polarity of the synchronization signal of the second input system from the selector 101, adjusts the polarity and level, and provides the synchronization signal and the polarity detection information to the control microcomputer 111.

The control microcomputer 111 includes a synchronization processing unit 106
If the pulse cannot be confirmed before the predetermined time elapses based on the pulse of the synchronization signal from and 107, it is determined that there is no synchronization signal. Further, even if a pulse of the synchronization signal is confirmed until the predetermined time elapses, if the frequency of the pulse deviates greatly from the corresponding frequency of the display device 112, it is determined that there is no synchronization signal.
For example, UXGA horizontal resolution 1600 × vertical resolution 12
00 and the corresponding horizontal synchronization frequency is 15.6 to 108.5 kHz
z, when the display device has a corresponding vertical synchronization frequency of 50 to 120 Hz, the horizontal synchronization frequency Hs is Hs ≦ 10 kHz,
Hs ≧ 115kHz, vertical synchronization frequency Vs is Vs ≦ 25H
When z, Vs ≧ 130 Hz, it is determined that there is no synchronization signal. A pulse of the synchronizing signal is confirmed until a predetermined time elapses, and the frequency of the pulse is displayed on the display device 11.
If the frequency does not deviate greatly from the corresponding frequency of 2, it is determined that there is a synchronization signal.

When the control microcomputer 111 determines that there are both a synchronization signal from the first input system to the synchronization processing unit 106 and a synchronization signal from the second input system to the synchronization processing unit 107, the screen synthesis is performed. A switch command for switching to two screens is sent to the / switching unit 108, and the video from the first input system and the video from the second input system (video from the image processing units 104 and 105) are displayed on the display device 112 in two screens. Display.

The control microcomputer 111 determines that there is no synchronization signal from the first input system to the synchronization processing unit 106,
When it is determined that there is a synchronization signal from the input system to the synchronization processing unit 107, a command to switch to one screen is sent to the screen combining / switching unit 108, and the video from the second input system (from the image processing unit 105). ) Is displayed on the display device 112 on one screen.

The control microcomputer 111 determines that there is no synchronization signal from the second input system to the synchronization processing unit 107, and
When it is determined that there is a synchronization signal from the input system to the synchronization processing unit 106, a command to switch to one screen is sent to the screen combining / switching unit 108, and the video from the first input system (from the image processing unit 104). ) Is displayed on the display device 112 on one screen.

The synchronization processing unit 1 from the first input system
06, synchronization processing unit 1 from second input system
If it is determined that there is no synchronization signal to the control signal 07, the control microcomputer 111 sets the synchronization signal generation units 109 and 110 at the time of no signal. Thereby, the A / D converter 10
2 and 103, the image processing units 104 and 105, the screen synthesizing / switching unit 108, and the synchronizing signal to the display device 112 are maintained, and screen disturbance and operation instability due to loss of synchronization are eliminated.

In this case, the A / D converters 102, 103,
Since the video signals to the image processing units 104 and 105 are no signals or abnormal signals (signals not synchronized properly), the control microcomputer 111 sets the screen combining / switching unit 1
08 is set so as to be replaced with a full-screen black or gray video signal that is properly synchronized (video mute processing). Alternatively, a setting is made to replace the output with a full-screen blue video signal that is properly synchronized and output (blue-back processing). At this time, if there is a difference in brightness, color, etc. between the two screens of the two systems, the control microcomputer 1
11 to the screen composition / switching unit 108 from
The mode may be switched to the one-screen mode by one of the signals of the system.

[Video Signal after A / D Conversion]
And the video signal of the second input system is supplied to the A / D converter 102
And 103, and converted into a digital signal by a sampling clock obtained by a PLL (phase comparison) of the synchronization signal generation units 109 and 110 so that the phase becomes a phase corresponding to the input signal. The video signal converted into a digital signal is subjected to resolution conversion and enlargement / reduction processing in image processing sections 104 and 105, processed into an image suitable for displaying one screen and two screens, and a screen synthesis / switching section 108. , A process of switching between one screen and two screens is performed and displayed on the display device 112.

Setting of resolution conversion and enlargement / reduction processing by the image processing units 104 and 105 and a screen synthesizing / switching unit 108
For the setting of the combination of two screens and the processing of switching between one screen and two screens and the operation setting of the display device 112, the control microcomputer 111 outputs setting data adapted to the input signal.

The synchronizing signals generated by the synchronizing signal generators 109 and 110 (the input signal and the synchronizing signal generated so as to have a timing suitable for each of one screen and two screens)
Image processing units 104 and 105 and screen combining / switching unit 10
8. Output to the display device 112 at an individual timing. Synchronization signal generators 109 and 110
Indicates that the setting data adapted to the input signal
The synchronization signal is generated by being output from the control signal 1.

The frequency of the input signal is determined by the control microcomputer 111 using the synchronization signals from the synchronization processing units 106 and 107,
The control microcomputer 111 receives the synchronization pulse polarity discrimination signals from 06 and 107 and compares the values with the unique information of the signal stored in the internal memory of the control microcomputer 111 to discriminate.

For example, a VG having a refresh rate of 60 Hz
The A signal (horizontal resolution 640 × vertical resolution 480) has a horizontal synchronization frequency of 31.47 kHz ± several kHz, a vertical synchronization frequency of 60 Hz ± several Hz, a horizontal synchronization polarity of negative polarity,
SVGA signal with a vertical sync polarity of negative polarity and a refresh rate of 75 Hz (horizontal resolution 800 x vertical resolution 600)
Is specific to the signal for which the input is assumed, such as a horizontal synchronization frequency of 46.88 kHz ± several kHz, a vertical synchronization frequency of 75 Hz ± several Hz, a horizontal synchronization polarity of positive polarity, and a vertical synchronization polarity of positive polarity. Is stored in the internal memory of the control microcomputer 111.

[Embodiment 4 (Specific Example 2)] FIG.
FIG. 14 is a block diagram showing a modification of the display device with a two-screen function shown in FIG. In the display device having the two-screen function, the plug-in detectors 116-1 to 116-11 are respectively provided for the input systems I to V.
6-5 is provided, and the detection result (the result of whether or not the input device is connected to the input systems I to V) is supplied to the control microcomputer 111 via the insertion detection unit 117.
In this embodiment, the control microcomputer 111 controls the input systems I to V based on the detection result from the plug-in detection unit 117.
The presence or absence of the connection of the input device to the input device is recognized, and two input systems are selected from the input systems to which the input device is connected, so that the input system is used for automatic switching between one screen and two screens.

The selection of an input system when the control microcomputer 111 automatically switches between one screen and two screens is performed, for example, as follows. The detection results (presence / absence of detection) of the plug-in detectors 116-1 to 116-5 and the order in which the plug-ins are detected (the order of connection of the input devices) are stored in the internal memory of the control microcomputer 111 or the nonvolatile memory 115. The control microcomputer 111 refers to the stored contents, sets the first input system in which the connection order of the input devices is the first input system, the second input system as the second input system, and sets the selector 101 as a selection condition using the input system as the selection condition. Give to. The selector 101 converts the two input systems specified by the selection conditions into input systems I to V based on the selection conditions given from the control microcomputer 111.
Choose from In this case, even if the user does not specify, 2
One input system is specified automatically.

In the OSD 114, one screen and two screens
LE to determine whether screen switching is automatic or manual
If the lighting of the light-emitting element such as D is performed, and the color coding is used,
Even when the menu is not displayed, the current state can always be recognized by the user, and the degree of understanding of the user can be improved.

Also, by replacing the operation button 113 with a communication interface such as a remote control light receiving element or RS-232C or by using it together, it is possible to set whether the switching between one screen and two screens is automatic or manual. It can also be performed by remote control.

[0047]

As is apparent from the above description, according to the present invention, the presence / absence of the synchronizing signal of the video signal from the first input system is detected, and the video signal from the second input system is detected. The presence / absence of a synchronization signal is detected. If both the detection results of the presence / absence of the synchronization signal of the video signal from the first and second input systems include the presence of the synchronization signal, the first input system and the second input system Is displayed on two screens on one display device, and when one of the detection results of the presence / absence of the synchronization signal of the video signal from the first and second input systems has the presence of the synchronization signal, the presence of the synchronization signal is present. 1 video from input system
Since one screen is displayed on one display device,
For example, the video from the first input system is
When a synchronization signal of a video signal from the second input system is detected while being displayed on the screen, a two-screen display is automatically performed, and when the synchronization signal of the video signal from the second input system is lost. Is automatically displayed on a single screen, and it is possible to automatically switch between one screen and two screens without giving a switching signal from the outside.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main part of a basic example 1 (first embodiment) of a display device with a two-screen function according to the present invention.

FIG. 2 is a diagram showing a two-screen display operation and a one-screen display operation of the display device.

FIG. 3 is a block diagram illustrating a main part of a basic example 2 (Embodiment 2) of the display device with a two-screen function according to the present invention.

FIG. 4 is a block diagram of a display device with a two-screen function that embodies Basic Example 2 (Embodiment 3).

FIG. 5 is a block diagram (fourth embodiment) showing a modification of the display device with a two-screen function shown in FIG. 4;

[Explanation of symbols]

1, 1 '... display device with two-screen function, 1-1, 1-2 ...
Synchronization signal presence / absence detection section, 1-3 ... 2 screen / 1 screen switching section,
1-4: display device, 1-5: input system selection unit, 1-
6 ... setting data storage unit, 2-1 to 2-n ... signal source, 10
1 selector, 102, 103 A / D converter, 10
4, 105: Image processing unit, 106, 107: Synchronization processing unit, 108: Screen synthesis / switching unit, 109, 110: Synchronization signal generation unit, 111: Control microcomputer, 112: Display device, 113: Operation button, 114 ... On-screen device (OSD), 115 ... non-volatile memory, 116-
1 to 116-5: insertion detector 117: insertion detector

Claims (3)

[Claims] 1. A first synchronization signal detecting means for detecting the presence or absence of a synchronization signal of a video signal from a first input system, and a second detection means for detecting the presence or absence of a synchronization signal of a video signal from a second input system. And if both of the detection results of the first and second synchronization signal detection means indicate that there is a synchronization signal, the video from the first input system and the second input system is displayed on one display device. When one of the detection results of the first and second synchronization signal detection means has a synchronization signal, an image from an input system having a synchronization signal is displayed on the display device on one screen. A display device having a two-screen function. 2. An input system selecting means for selecting two input systems specified from n (n ≧ 3) input systems as a first input system and a second input system, and the first input system A first synchronization signal detecting unit for detecting the presence or absence of a synchronization signal of a video signal from the second input unit; a second synchronization signal detection unit for detecting the presence or absence of a synchronization signal of a video signal from the second input system; If both the detection results of the first and second synchronization signal detecting means include a synchronization signal, the video from the first input system and the second input system is displayed on one display device on two screens, Display means for displaying, on one screen, an image from an input system having a synchronization signal on one screen when one of the detection results of the first and second synchronization signal detection means has a synchronization signal. Characteristic display device with two-screen function Place. 3. The method according to claim 1, wherein the first and second synchronization signal detecting means determine a predetermined value based on a pulse of a synchronization signal of a video signal from the first input system and the second input system. A two-screen display characterized by determining that there is no synchronization signal when the pulse cannot be confirmed before the time elapses, or when the frequency of the pulse deviates greatly from the corresponding frequency of the display device. Display with function.